Mary Konye, 21, allegedly followed Naomi Oni home from her work at Victoria’s Secret lingerie shop in Westfield Stratford City before attacking the shop assistant in Lodge Avenue, Dagenham, for once calling her ugly.

Ms Oni, also 21, suffered serious burns to her face and chest, lost her hair and eyelashes and was left scarred for life by the attack on December 30, 2012.

The following day Konye sent a mobile phone message to her unsuspecting friend, who was in hospital receiving treatment, saying: “OMG, can’t believe it.”

The attack is alleged to have been a copycat of one suffered by model and TV presenter Katie Piper, who was badly scarred and left blind in one eye in a 2008 assault arranged by ex-boyfriend Daniel Lynch.

Ms Oni told Snaresbrook Crown Court that her friend was aware of how much an impact Piper’s ordeal had on her after watching a television documentary about it.

The pair fell out in April 2011 when Ms Oni allegedly accused Konye of texting her boyfriend and called her an “ugly monster”.

Konye is alleged to have responded by calling Ms Oni a “slag” and a “ho”.

They did not speak between April and September that year, but then took up the relationship again.

Ms Oni told the jury of eight men and four women that her friend was “insecure” about her looks.

“Normal things that girls would do, like take pictures, she wouldn’t participate in,” she said. “She wasn’t really one to like people talking about her in general.”

After the attack Ms Oni had skin graft surgery, with skin from her right leg removed to cover her burns.

Describing the moment she was attacked, she said: “I immediately felt that someone was trying to kill me and so my instinct was to run as fast as I could to get home.”

Konye and Ms Oni had been friends since secondary school before the attack happened near the victim’s home in Dagenham, east London.

During their school days the pair shared a “private joke” about 2003 horror movie Wrong Turn, which features disfigured characters and scenes of cannibalism, Ms Oni told the jury.

She said: “For example if people at school would laugh at us or bully either of us we would laugh with each other and say ‘Oh, you’re from Wrong Turn’ to insult them back.”

It is alleged that after the attack Konye posted a picture of the deformed Freddy Krueger character from terror movie Nightmare on Elm Street, together with the message: “Who looks like Wrong Turn now?”

CCTV footage obtained by police after the attack showed a figure in a niqab following Ms Oni as she left work at Westfield shopping centre in Stratford at around 11.30pm.

Hertfordshire University business and finance student Konye, of Canning Town, East London, denies throwing or casting a corrosive fluid with intent to burn, maim, disfigure, disable or do grievous bodily harm.

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